GENOTYPE OF WHEAT AND BARLEY AFFECTS LIGHT PENETRATION AND WILD OAT GROWTH

Cereal breeders have selected for traits that confer resistance to dis eases and insects, with the goal of stabilizing yield potential and re ducing inputs. The possibility exists that, by selecting for growth ha bits that impede weed development, cultivars can be developed ,sith in creased tolerance to weed infestations. Our objective was to determine whether wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) lines differ in their ability to prevent penetration of light into int errow spaces and suppress wild oat (Avena fatua L.) growth. Based on o ur results, significant genotypic variation exists within winter and s pring wheat and spring barley for the amount of sunlight allowed to pe netrate to interrow spaces. A negative correlation existed between hei ght and light penetration in four of seven nurseries studied. Six barl ey lines and six spring wheat lines, of similar heights but allowing d ifferent amounts of light penetration, were tested for suppression of wild oat growth. Barley was a much better competitor with wild oat tha n wheat was, allowing approximately one-half the wild oat biomass and seed production. Barley Lines allowed approximately 43% less light pen etration than wheat. Significant variation for wild oat growth variabl es also existed among lines within the crops. High positive correlatio ns of light penetration with wild oat growth existed within barley, su ggesting that lines may be selected to contribute to integrated wild o at management.